BRC-BIO: Understanding tree phloem functioning during drought

在这个气候变化相对极端的时代，了解植物如何与气候相互作用，准确预测未来的气候条件，并为二氧化碳减排工作提供信息是至关重要的。目前，森林每年吸收超过25%的人为二氧化碳排放。然而，目前尚不清楚它们吸收二氧化碳的能力在未来将如何变化，特别是在预计干旱会增加的地区。这个项目将调查我们对树木如何应对干旱的不确定性的一个关键未知因素：韧皮部。韧皮部是植物的“糖高速公路”。它是将叶片中光合作用的糖输送到需要糖生长的地方的管道。如果韧皮部在干旱期间失去功能，那么将糖运送到需要的地区的能力就会减少光合作用，甚至导致植物死亡。本项目将研究森林树木韧皮部在干旱环境下的功能。我们将使用新颖的拉曼光谱方法，使我们能够可视化整个植物的糖和量化韧皮部功能，以及其他方法。此外，该项目将侧重于通过与邻近的霍利奥克社区学院的学生和教师合作，将艺术融入研究过程，并为史密斯学院的学生提供研究机会，为来自代表性不足的社区的学生增加研究经验的可用性和质量。预计全球干旱的强度和频率都会增加。该项目旨在通过研究干旱下整个植物生理的韧皮部功能，进一步了解树木对干旱的反应。韧皮部负责将糖从生产地点运送到需要的地点，并由水产生的正压驱动。由于韧皮部在整个植物功能中的重要作用及其对水分的依赖性，韧皮部被认为是干旱反应（如光合作用下调和死亡）的关键调节因子。本提案的目标有三个方面：量化成熟森林树木在控制和干旱条件下韧皮部功能的差异，了解韧皮部何时失去与光合作用有关的功能，并研究韧皮部功能与植物死亡率的关系。我们将通过使用拉曼光谱和测量碳在韧皮部中的移动速率以及其他生理方法来实现这些目标。建立森林降雨调控实验，并将其用于美国东北部树种树苗在受控环境下的控制死亡率实验。该项目将提高我们对干旱条件下韧皮部功能的理解，进而提高对整个树功能的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this time of relatively extreme climate change, it is crucial that we understand how plants interact with the climate, to accurately predict future climate conditions and to inform CO2 mitigation efforts. Currently, forests sequester upwards of 25% of anthropogenic CO2 emissions, annually. However, it is unclear how their ability to sequester CO2 will change in the future, especially in areas that are predicted to have increased droughts. This project will investigate a key unknown underlying our uncertainty around how trees respond to drought: the phloem. The phloem is the “sugar highway” of the plant. It is the pipe that transports sugars that are photosynthesized in leaves to areas that need sugar to grow. If the phloem loses functioning during drought, the resultant lack of an ability to transport sugars to areas in need could reduce photosynthesis or even cause plant mortality. This project will investigate how phloem functions in the context of drought for forest trees. We will use novel Raman spectroscopy methods that allow us to visualize sugar throughout the plant and quantify phloem functioning, among other methods. Additionally, this project will focus on increasing the availability and quality of research experiences for students from under-represented communities through collaborating with students and faculty from the neighboring Holyoke Community College, integrating art into the research process, and providing research opportunities for Smith College students.Droughts are predicted to increase in intensity and frequency around the world. This project seeks to further our understanding of how trees respond to drought by investigating phloem function in whole-plant physiology under drought. The phloem is responsible for transporting sugar from sites of production to sites of need and is driven by positive pressure generated by water. Due to its integral role in whole plant function and its dependence on water, the phloem is hypothesized to be a key regulator of drought responses e.g., photosynthetic down-regulation and mortality. The objectives of this proposal are three-fold: to quantify differences in phloem function during control and drought conditions for mature, forest trees, to understand when the phloem loses function in relationship to photosynthesis, and to investigate how phloem functioning relates to plant mortality. We will approach these objectives through the use of Raman spectroscopy and measuring the rate at which carbon moves in the phloem, alongside other physiological methods. A forest rain-fall manipulation experiment will be established and used in controlled mortality experiments on saplings of northeastern US tree species in controlled environments. This project should improve our understanding of phloem function, and subsequently whole-tree function, in drought conditions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.